The calibration of cylindrical hot-film velocity sensors

Ten hot-film velocity sensors with aspect ratios near 20 were calibrated for Reynolds numbers from 1 to 18. This calibration required investigating the yaw angle dependence of the sensors and determining a zero-wind Nusselt number for each. Conduction heat losses to the sensors supports vary from sensor to sensor and, thus, affect both the velocity calibration and the zero-wind Nusselt numbers. Nevertheless, because these losses are velocity independent, with knowledge of zero-wind Nusselt numbers their effects can be eliminated from the heat transfer relation for small aspect ratio hot-films.